1. Field of Invention
This invention relates to an improvement in an assaying method as used in the immuno-serologically and pathologico-histologically qualitative and quantitative determination of a biocomponent, and to a method for diagnosing cancer according to the assaying method.
2. Prior Art
The following methods have been known so far for detection of a biocomponent, for example, serum protein: coloring matter-staining method, silver stain method, autoradiographical method, immunological method using a labelled antibody, for example, enzyme immunoassay (EIA), fluoroimmunoassay (FIA), radioimmunoassay (RIA), etc. As the enzyme immunoassay, the method of Takeda, et al. is known (Electrophoresis 1983, 4, 371-373). Diagnosis of cancer has been carried out so far according to these methods.
The coloring matter-staining method is high in background, unclear, and poor in detection sensitivity.
The silver stain method and the autoradiographical method are high in sensitivity and accuracy, but complicated in operational procedures, and cannot be carried out promptly and simply. On account of using heavy metals and isotopes, they have a waste disposal problem, and furthermore their measurement items are limited, so that they have no wide application.
The immunological methods can specifically detect a single substance, and have a very high measuring sensitivity, a distinguished quantitative determination and a wide application. However, the radioimmunoassay has problems in radiation exposure, handling control, waste disposal, etc. owing to the use of radioisotopes. The fluoroimmunoassay has a complicated operational procedure and no applicability to double staining and thus has a limited application. It is said that the enzyme immunoassay generally has a high detecting sensitivity and is clear and comparatively simple and rapid in operational procedures. However, the conventional method for coloring in a gel-like carrier, using an enzyme-labelled antibody has problems of high background, uncleanness, low sensitivity, etc.
When biocomponents are supported on a gel-like carrier or a carrier membrane and developed by electrophoresis, the control marker for the migration is generally made to migrate apart from the biocomponents but in parallel to the biocomponents. This method has problems such as poor reproducibility of migration distances of biocomponents, low accuracy in measurements, etc.
A method for applying the enzyme immunoassay to a coloring system in a gel-like carrier has been little known, and no thorough studies have been made of optimum conditions for the reaction, that is, combinations with an enzyme, a substrate, etc. of a receptor capable of being specifically bound to a target substance.